In a talent show, a juggler juggles 4 balls simultaneously, as shown in the figure. A spectator uses his high speed video tape and determines that it takes the juggler 1s to cycle each ball through his hands (including catching, transferring and throwing) and to be ready to catch the next ball. It is noted that at most one ball must be in the hand of the juggler in each cycle of juggling. What is the minimum vertical speed the juggler must throw up each ball? g=10 ms-2